Dishwashing machine



Sept. 9, 1969 L. w. GUTH DISHWASHING MACHINE 2 Sheets-Sheet 1 Filed May 1, 1968 FV'IGJ H\S ATTORNEY Sept. 9, 1969 Filed May 1, 1968 CAM L. W. GUTH DISHWASHING MACHINE 2 Sheets-Sheet 2 lst NOR MAL. PRE'R\NSE DRAIN UP Ann DOWN RINSE is": NORMAL 2m. NOR

LAST NORMAL LAUREN W GUTH H\ S ATTORNEY United States Patent US. Cl. 134-58 9 Claims ABSTRACT OF THE DISCLOSURE An automatic dishwasher comprising a washing enclosure for receiving and containing articles to be washed therein, means for supplying liquid to the enclosure, first and second spray means within the enclosure for affecting a washing action on the articles by respectively ejecting pressurized liquid generally upwardly and downwardly thereon, and circulating means for circulating liquid from the enclosure to the spray means. The circulating means includes concurrently operable first and second pump means. The first pump means has an inlet connected to the enclosure and an outlet connected to the upwardly ejecting first spray means. The second pump means has an inlet connected to the enclosure at an elevation lower than that of the inlet of the first pump means and has an outlet connected to the downwardly ejecting second spray means. Control means are provided for periodically limiting liquid supplied to the enclosure by the supply means to an amount such that only the second pump means is primed thereby and concurrent operation of the two pump means will then cause liquid to be ejected only downwardly on the articles.

BACKGROUND OF THE INVENTION This invention relates generally to an automatic dishwasher and more particularly to means for reducing redeposition of food solids on articles washed in automatic dishwashers.

Many conventional dishwashers include a washing enclosure vertically-spaced upper and lower racks for supporting articles to be washed in the enclosure, means for supplying liquid to the enclosure including an electricallyoperated inlet valve, first and second spray means located in the upper and lower portions of the enclosure for affecting a washing action on the articles by respectively ejecting pressurized liquid generally upwardly and downwardly thereon, and an electrically-operated motor-pump assembly vertically arranged in the bottom of the enclosure and including superimposed upper and lower pumps that are alternatively operated by a single reversible electric motor either to circulate liquid from the enclosure through both of the two spray means or to discharge liquid from the enclosure to a drain connected to a second outlet from the lower pump. U.S. Patent No. 3,079,094, issued Feb. 26, 1963 to B. J. Brezosky et a1. and assigned to the General Electric Company, assignee of the present invention, describes a typical one of such conventional dishwashers.

The operational sequence of such conventional dishwashers usually involves in order, one or more pre-rinse periods, a wash period, and one or more post-rinse periods. The last post-rinse period is normally followed by a drying period wherein the dishes are heated by an electrical heating element to facilitate their drying. Control means are provided to sequentially energize and de-energize the various electrically-operated components of the dishwasher to carry out the operational cycle. Generally, a sequence control means having a timer motor and several cam-operated switches is provided, with each switch controlling one of the components. In such conventional machines, the electrically-operated inlet valve is usually of a type which, when opened, passes liquid at a fixed Patented Sept. 9, 1969 volumetric rate. Hence, the amount of liquid admitted to the enclosure is proportional to the length of time that the inlet valve is opened by its cam-operated switch in the sequence control means. Conventionally, the cam for that switch is so configured and arranged that each time it opens the inlet valve, it will maintain the same open long enough to admit a sufficient volume of liquid into the enclosure so that both the upper and lower pumps of the pump assembly will be primed and operation of the pump assembly can then cause the liquid to be ejected from both upwardly and downwardly ejecting spray means. US. Patent No. 3,286,149 issued Nov. 15, 1966 to D. S. Cushing and assigned to the General Electric Company, assignee of the present invention, describes typical operational sequence control means for such conventional dishwashers.

In such conventional dishwashers, the articles which have the most food solids, such as pots, pans, plates and platters, are usually located within the lower rack, while the articles having lesser amounts of food solids, such as glasses and like, are usually located within the upper rack. During conventional initial operation of such machines, wherein liquid is sprayed from both the upwardly and downwardly ejecting spray means, the food solids on the lower rack articles are propelled upwardly by the liquid sprayed from the upwardly ejecting spray means and redeposited on the upper rack articles. Such conventional initial operation presents a particularly severe problem with the upwardly propelled solids that are redeposited within the interiors of inverted glasses that are located with the upper rack. Hence, it would be desirable to provide means for automatically instituting initial operations wherein liquid would be sprayed only from the downwardly ejecting spray means to thus drive the food solids into the bottom of the enclosure and wherein the liquid and removed solids would be pumped from the enclosure bottom to drain prior to the commencement of subsequent operations of the machine wherein liquid is ejected both upwardly and downwardly from both of the spray means. Such initial downward only spray and drain operations would greatly reduce the amount of solids which would otherwise be initially propelled upwardly into the enclosure and ultimately redistributed throughout the enclosure during subsequent rinse, wash and post rinse periods and, hence, would greatly reduce redeposition of solids on the articles.

SUMMARY OF THE INVENTION In accordance with the present invention, it has been found that such desirable initial downward only spray and drain operations can be incorporated into a conventional dishwasher of the type described above by providing means for periodically limiting the volume of liquid admitted by the liquid supply means to the washing enclosure to an amount such that only the lower one of the two pumps is primed thereby and the liquid is then sprayed by only the downwardly ejecting one of the two spray means during the initial concurrent operation of the two pumps. In one form of the present invention, the means for periodically limiting the volume of liquid admitted to the enclosure is provided by modifying the configuration and arrangement of the cams for the camoperated switches in the sequence control means which control the electrically-operated inlet valve and the electrically-operated motor-pump assembly in such a manner that only enough liquid is admitted to prime the lower pump and operation of the motor-pump assembly will cause liquid to be sprayed from only the generally downwardly ejecting one of the two spray means.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustrated in the accompanying drawings, wherein:

FIGURE 1 is a right side elevational view partly cut away to show details, of an automatic dishwasher incorporating a presently preferred form of the present invention;

FIGURE 2 is an enlarged fragmentary elevational view, with parts broken away and parts in section, of the pumping mechanism installed in the bottom of the washing enclosure of the dishwasher of FIGURE 1;

FIGURE 3 is a schematic representation of the electrical circuitry of the control system for the form of the present invention illustrated in FIGURE 1; and

FIGURES 4 and 5 are sequence control cam charts illustrating a presently preferred sequence of operation of the schematically shown switches in FIGURE 3, with FIGURE 4 showing the early portion of the operational sequence and FIGURE 5 showing the later portion.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and particularly to FIGURE 1 thereof, there is shown an automatic washing machine in the form of an automatic dishwasher having an outer cabinet 11 defining therein a washing enclosure 12. Disposed within the washing enclosure 12 are a pair of vertically spaced upper and lower racks 13 and 14 that are adapted to receive and support dishes or other articles (not shown) to be washed within the washing enclosure 12. A door 15 is provided in the front wall of the cabinet 11, pivotal about hinge means 16 to provide access to the washing enclosure 12. When the door 15 is pivoted downwardly, the upper rack 13 can be at least partially withdrawn from the upper portion of the washing enclosure 12 by means of the slide and roller system 17 provided at each side of the upper rack 13 and slidably supporting the upper rack 13 on the inner side walls of the cabinet 11. Similarly, the lower rack 14 can be at least partially extended from the lower portion of the washing enclosure 12 by means of a roller 18 which rides upon a track 19 provided on each inner side wall of the cabinet 11.

Means including an electrically-operated inlet valve 20 are provided for supplying water, or other liquids, to the washing enclosure 12. A conduit 21 interconnects the inlet of the valve 20 with a source of hot water (not shown) and another conduit 22 interconnects the oulet of the valve 20 with an inlet port 23 formed in one wall of a washing enclosure 12 at a point sufliciently elevated to preclude the loss of wash fluids therethrough. An electrical resistance heating element 24 is provided in the washing enclosure 12 to facilitate drying of the articles after they have been washed and, if desired, to assist in heating wash fluids in the washing enclosure 12 during the washing operation.

Spray means are provided within the washing enclosure 12 for affecting a washing action on the articles contained therein by ejecting pressurized liquid thereon. As illustrated in FIGURE 1, the spray means include first spray means, comprising a lower spray arm 25 that is positioned below the lower rack 14 for rotation about a vertical axis to eject liquid generally upwardly on the articles and second spray means, comprising an upper spray arm 26 that is positioned above the upper rack 13 for rotation about a vertical axis to eject liquid generally downwardly on the articles.

Referring now to FIGURE 2 in conjunction with FIG- URE 1, it is seen that the bottom of the washing enclosure 12 is defined by a bottom wall 27 which has a centrally depressed portion forming a sump 28 that receives liquid admitted by the inlet valve 20.

Means are provided for circulating liquid from the sump 28 to the first and second spray means 25 and 26 and comprise a motor-pump assembly 29 that is vertically arranged within an opening 30 provided in the enclosure bottom wall 27. The motor-pump assembly 29 includes superimposed first and second pump means 31 and 32 that are concurrently operable by a reversible electric motor 33. The first pump means or upper pump 31 includes an axial-flow type impeller 34 connected to the upper end of the motor output shaft 35 for rotation therewith within an upper pump housing 36. The upper pump housing 36 has a radial inlet 37 that is fluid connected to the washing enclosure sump 28 and an outlet 38 that is connected to the first spray means or lower spray arm 25. The second pump means or lower pump 32 includes a centrifugal-type pump impeller 39 connected to the lower portion of the motor output shaft 35 for rotation therewith within a lower pump housing 40. The lower pump housing 40 has an axial inlet 41 that is fluid connected to the sump 28 at an elevation lower than that of the inlet 37 for the upper pump housing 36 and has an outlet 42 that is connected by a riser conduit 43 to the second spray means or upper spray arm 26. The lower pump housing 40 has another outlet 44 which is connected by a conduit (not shown) to a drain (not shown) in a well-known manner.

The foregoing structure is generally similar to that described in the aforementioned US. Patent No. 3,079,- 094, and, when the pump motor 33 is energized to rotate its output shaft 35 in a first or circulate direction, the upper and lower pump impellers 34 and 39 are concurrently operated thereby in such a manner that if liquid is present at both the upper and lower inlet-s 37 and 41 both the upper and lower pumps 31 and 32 will be primed thereby and liquid will be pumped under pressure to both the upper and lower spray arms 26 and 25. When the motor 33 is energized to rotate its shaft 35 in a reverse or drain direction, both of the impellers 34 and 39 will be rotated, but only the lower impeller 39 will act to draw the liquid through the lower inlet 41 to discharge the same through drain outlet 44.

A sequence control means 45 having a manually operable knob 46 is conveniently positioned on the door 15. The sequence control means 45 is disposed within the door 15 and the knob 46 projects out through the front wall of the door 15 to be conveniently manipulated by the operator of the dishwasher 10.

Referring now to FIGURES 3-5, the control system for a presently preferred embodiment of the present invention and its predetermined sequence of operation are schematically and graphically represented. The control system comprises the sequence control means 45 which includes a synchronous electric timer motor 47 that drives a plurality of cams 48-52 that control, respectively, a plurality of switch elements 5357. The knob 46, timer motor 47 and cams 4852 are, of course, mechanically interconnected in a well-known manner.

Power is introduced into the control system through terminals L1 and L2. A master switch 58 is operative with the closing of the door 15 such that the control system cannot be energized until the door 15 is securely closed. The switch 53 controls the energization of the timer motor 47, which, when energized drives all of the cams 48-52. The switch element 55 controls the opening and closing of the liquid inlet valve 20 and, when closed, energizes a solenoid 20a to open the inlet valve 20. The switch element 54 controls energization of the heating element 24. The switch elements 56 and 57 control the operation of the pump motor 33. The motor 33 includes a run winding 59 and a pair of start windings 61 and 62. The switch element 56 controls the energization of both the run winding 59 and one of the start windings 60 and 61, and the switch element 57 determines which of the start windings 60 or 61 is energized upon the closing of the switch element 56.

The liquid inlet valve 20 is of a well-known type and is operated by the solenoid 20a. When the solenoid 20a is energized by closure of the cam-operated switch element 55, the liquid inlet valve 20 is fully opened. When the switch element 55 is open, the valve 20 is fully closed. The valve 20 is of the type that, when in its fully open position, passes liquid at a fixed volumetric rate. Hence the volumetric amount of liquid admitted to the washing enclosure 12 is proportional to the length of time that the inlet valve 20 is opened through energization of its solenoid 20a by closure of the switch element 55 by the cam 50.

The conventional configuration and arrangement of the cams 48-52 is usually such that a conventional complete operational cycle of the dishwasher involves in order: one or more pre-rinse periods; a wash period; and one or more post-rinse periods. The last post-rinse period is normally followed by a drying period wherein the articles are heated by the electrical resistance heating element 24 to facilitate their drying. Each of the conventional prerinse, wash and post-rinse operations includes in order: (1) a fill period wherein the pump motor 33 is deenergized and the water inlet valve 20 is opened to admit liquid to the washing enclosure 12, (2) a rinse or wash period wherein the liquid inlet valve 20 is closed and the pump motor 33 is energized to cause the motor output shaft 35 to rotate in its first or circulate direction, and (3) a drain period wherein the liquid inlet valve 20 remains closed and the pump motor 33 is energized to rotateits shaft 35 in a reverse or drain direction. The conventional configuration and arrangement of the cam 50- is such that the switch 55 will be closed for a sufficient length of time during each of the conventional or normal fill periods to admit enough liquid to the washing enclosure 12 so that both the upper and lower pumps 31 and 32 will be primed during each of the subsequent conventional rinse or wash periods and liquid will then be ejected from both the upper and lower spray arms 26 and 25.

As previously noted, the articles having the most gross food solids, such as pots, pans, plates and platters are usually located in the lower rack 14 within the lower portion of the washing enclosure 12, and it would be desirable to provide means for spraying liquid only downwardly on these articles and then pumping the liquid and the entrained solids thus removed by it out of the wash ing enclosure 12 to the household sewer system or drain before initiating any conventional spraying operations in which liquid is ejected both upwardly and downwardly on the articles. In accordance with the present invention, it has been found that such a desirable initial downwardly only spraying or rinsing operation can be incorporated into the conventional dishwashers of the foregoing type by providing means for periodically limiting the volume admitted by the liquid inlet valve 20 to the washing enclosure 12 to an amount such that only the lower pump 32 is primed.

As best illustrated in FIGURES 3 and 4, this is accomplished in the presently preferred embodiment of the present invention by so modifying of the configuration of the cams 4852 of the sequence control means 45 such that the early portion of the operational cycle for the dishwasher 10 includes in order:

1) An initial short fill period in which the cams 51 and 52 operate the switch elements 56 and 57 to deenergize the pump motor 33, and the cam holds the switch element closed just long enough to open the inlet valve 20 to admit only enough liquid to the washing enclosure 12 to prime the lower pump 32;

(2) A downward only rinse period in which the cam 50 operates to open the switch element 55 and close the inlet valve 20, and the cams 51 and 52 operate the switch elements 56 and 57 to energize the motor windings 59 and of the pump motor 33 to rotate its shaft 35 in the circulate direction causing liquid to be circulated only by the primed lower pump 33 to only the downwardly ejecting upper spray arm 26;

(3) An initial drain period in which the cam 50 operates to retain the switch element 55 in its open position and the inlet valve 20 closed, and the cams 51 and 52 operate the switch elements 56 and 57 to energize the motor windings 59 and 61 of the pump motor 33 to rotate its shaft 35 in the reverse or drain direction causing liquid and entrained removed food solids to be discharged from the enclosure 12 by the lower pump 32 through the drain outlet 44;

(4) A second short fill period in which the earns 51 and 52 operate the switch elements 56 and 57 to deenergize the motor 33, and the cam 50 holds the switch element 55 closed just long enough to open the inlet valve 20 to admit only enough liquid to the washing enclosure 12 to prime the lower pump 32; and

(5) A second drain period in which the cam 50 operates to open the switch element 55 and thus close the inlet valve 20, and the cams 51 and 52 operate the switch elements 56 and 57 to energize the motor windings 59 and 61 of the pump motor 33 to cause its shaft 35 to rotate in the drain direction causing liquid and entrained food solids to be discharged from the Washing enclosure 12 by the lower pump 32 through the outlet 44.

As illustrated in FIGURES 3-5, the remainder of the dishwasher operational cycle immediately follows the second drain period and preferably includes two normal pre-rinse periods, a normal wash period and three normal post-rinse periods followed by a drying period. As illustrated in FIGURES 4 and 5, each of these normal pre-rinse, wash and post-rinse periods includes in order:

(1) A normal fill period in which the cams 51 and 52 operate the switch elements 56 and 57 to de-energize the pump motor 33 and the cam 50 holds the switch element 55 closed long enough to open the valve 20 such that enough liquid is admitted to the washing enclosure to prime both the upper end lower pumps 31 and 32;

(2) An up and down wash or rinse period in which the cam 50 allows the switch element 55 to open and thus closes the inlet valve 20 and the cams 51 and 52 operate the switch elements 56 and 57 to energize the motor windings 59 and 60 causing the pump motor 33 to rotate its shaft 35 in the circulate direction causing both the upper and lower pumps 31 and 32 to circulate pressurized liquid to both the upper and lower spray arms 26 and 25;

(3) A drain period in which the cam 50 allows the switch element 55 to remain open and the inlet valve to remain closed and the cams 51 and 52 operate the switch elements 56 and 57 to energize the motor windings 59 and 61 to cause to energize the motor 33 to rotate its shaft 35 in the reverse or drain direction wherein the lower pump 32 discharges liquid and entrained food solids from the washing enclosure 12 through the lower pump drain outlet 44.

The cams 50, 51 and 52 are so configured and arranged as to allow the switch elements 55 and 56 to remain open following completion of the last post-rinse drain period, whereby the inlet valve 20 remains closed and the pump motor 33 remains de-energized for the balance of the operational cycle. The cam 49 is configured and arranged to allow the switch element 54 to remain open from the beginning of the operational cycle until the completion of the last post-rinse drain period, at which time it closes the switch element 54 and maintains the same closed and electrical heating means 24 energized for the balance of the operational cycle.

Of course, the configuration of the cam 48 is made such that when the control knob 46 is initially manually rotated a few degrees at the beginning of the operational cycle, the cam 48 closes the switch element 53 to energize the timer motor 47 and from that moment on retains the switch element 53 closed throughout the complete dishwasher operational cycle, whereby the timer motor 47 continues to drive all the cams 48-52 until the cam 48 allows the opening of the switch element 53 at the end of the operational cycle.

The durations of the various periods of the dishwasher operational cycle are of course dependent upon the sizes of the valve 20 and the washing enclosure 12 and the characteristics of the pumps 31 and 32. FIGURES 4 and illustrate typical time periods which have produced satisfactory results with an otherwise conventional dishwasher that has been modified in accordance with the foregoing teachings of the present invention.

Thus, it can be seen that the present invention provides a dishwasher having first and second spray means which are arranged to respectively eject pressurized liquid generally upwardly and downwardly upon articles contained within its washing enclosure to effect a washing action thereon and that are respectively supplied with pressurized liquid circulated from the washing enclosure by concurrently operated first and second pump means having inlets vertically spaced apart within the washing enclosure, with means for automatically periodically limiting the amount of liquid admitted to the enclosure to an amount such that only the pump means having the lower inlet will be primed and concurrent operation of the two pump means will result in liquid then being sprayed only downwardly upon the articles.

As will be evident in the foregoing description, certain aspects of the present invention are not limited to the particular details of construction of the examples illustrated and it is contemplated that various modifications or other applications may occur to those having skill in the art. For example, the common drive means for the two pump means might be a unidirectional motor and diverter valve means of a well-known construction might be employed to selectively shift the liquid discharge from the lower inlet pump means between the downwardly ejecting spray means and the drain outlet. It is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of the present invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An automatic dishwasher comprising:

(a) a washing enclosure for receiving and containing articles to be washed therein;

(b) liquid supply means for supplying liquid to said enclosure;

(c) spray means in said enclosure for affecting a washing action on the articles by ejecting liquid thereon, said spray means including (i) first spray means for ejecting liquid generally upwardly on the articles, and

(ii) second spray means for ejecting liquid generally downwardly on the articles;

((1) means for circulating liquid from said enclosure to said spray means including (i) first pump means having an inlet connected to said enclosure and an outlet connected to said first spray means,

(ii) second pump means having an inlet connected to said enclosure at an elevation lower than that of said inlet of said first pump means and an outlet connected to said second spray means, and

(iii) drive means for concurrently operating said first and second pump means; and

(e) control means for periodically limiting the liquid supplied to the enclosure by said liquid supply means to an amount such that only said second pump means is primed thereby and operation of said drive means will then cause liquid to be ejected only generally downwardly on the articles.

2. The invention of claim 1, wherein said control means includes:

(a) an electrically-operated valve in said liquid supply means; and

(b) sequence control means comprising a timer motor and switch means controlling the opening and closing of said valve and operated in a predetermined operation sequence by means driven by said timer motor.

3. The invention of claim 2, wherein:

(a) said valve is of a type wherein the amount of liquid supplied by said supply means to said enclosure is proportional to the length of time that said valve is opened; and

(b) said means driven by said timer motor comprises cam means so configured and arranged relative to said switch means that said predetermined operational sequence includes a period in which said valve is opened just long enough so that the amount of liquid supplied to said enclosure by said supply means during said period is only enough to prime said second pump means therewith.

4. The invention of claim 3, wherein said cam means are so configured and arranged relative to said switch means such that said period occurs during the initial operation of said valve during said predetermined operational sequence.

5. The invention of claim 1, wherein:

(a) said first spray means is in the lower portion of said enclosure; and

(b) said second spray means is in the upper portion of said enclosure.

6. The invention of claim 1, further including vertically-spaced upper and lower rack means for supporting the articles within said enclosure.

7. The invention of claim 6, wherein:

(a) said first spray means is below said lower rack means; and

(b) said second spray means is above said upper rack means.

8. The invention of claim 6, wherein:

(a) said first spray means is below said lower rack means; and

(b) said second spray means is above said lower rack means.

9. The invention of claim 6, wherein:

(a) said first spray means is below said upper rack means; and

(b) said second spray means is above said upper rack means.

References Cited UNITED STATES PATENTS 2,960,990 11/1960 Jones et al 134186 XR 3,084,701 4/1963 Hardy et a1 134186 XR 3,286,149 11/1966 Cushing 318-221 FOREIGN PATENTS 647,255 10/ 1962 Italy.

DANIEL BLUM, Primary Examiner US. Cl. X.R. 1341 86 

